TRANSACTIONS OF SECTION A. 659 
~The annual means at the ninety-nine stations- are: Oxford, eight stations, 
26:18 inches: Bucks, seven stations, 25:28 inches ; Herts, six stations, 25:87 inches ; 
Middlesex, three stations, 25:46 inches; Essex, thirteen stations, 23:68 inches; 
Berlis, eight stations, 27:28 inches; Hants, sixteen stations, 28:80 inches; 
Surrey, eight stations, 24:90 inches; Sussex, fifteen stations, 30:22 inches; and 
Kent, fifteen stations, 2641 inches; the mean for the whole area being 
26:80 inches. This differs very slightly from the mean at the seventy stations for 
which the monthly means are given. 
During the ten years, 1881 to 1890, the rainfall in this part of England was 
rather less than that for the twenty-five years ending 1890, and that for the 
thirty years ending 1895. Twenty stations give a mean for the ten years, 1881-90, 
of 26-22 inches, for the twenty-five years, 1866-90, of 27-74. inches, and for the 
thirty years, 1866-95, of 27:55 inches, the excess in this period thus being 
1:33 inches, or nearly 5 per cent. (4'8), over the mean fall at the same stations 
for the ten years 1881-90. The true mean for the larger number of stations for 
the thirty years would therefore probably be about 28 inches. 
The mean fall for the thirty years at the twenty stations in five-yearly periods 
was as follows: For the first lustrum, 18G6-70, 27:09 inches; for the second, 
1871-75, 27°76 inches; for the third, 1876-80, 31:41 inches; for the fourth, 
1881-85, 27:08 inches; for the fifth, 1886-90, 25°36 inches; and for the sixth, 
1891-95, 26°63 inches. 
The rainfall in these counties does not throughout follow the general rule of 
increase from east to west. It does so only from Essex, through Middlesex and 
Tlerts, to Bucks, north of the Thames, and from Kent to Sussex, south of the 
Thames. Dividing the counties into three groups, north, south-west, and south- 
east, thirty-seven stations for the northern group, Oxford, Bucks, Herts, Middle- 
sex, and Hssex, give an annual mean of 25:02 inches; thirty-two stations for the 
south-western group, Berks, Hants, and Surrey, give an annual mean of 
27-43 inches; and 30 stations for the south-eastern group, Sussex and Kent, give 
an annual mean of 28*32 inches. In the first group the driest months are March 
and April, each with a mean fall of 1:69 inch; in the second the driest month is 
April, with a mean fall of 1:80 inch; and in the third the driest month is J une, 
with the same mean fall. In the first group the wettest month is November, with 
a mean fall of 258 inches; in the second, the same month, with a mean fall of 
310 inches; and in the third, the wettest is October, with a mean fall of 
3°43 inches.: From October to April, and in June, Essex is the driest county ; in 
May, Kent; in July, Hants; in August, Surrey; and in September, Oxford. In 
February, and from July to December, Sussex is the wettest county; in January 
and March, Hants; in April, Berks; in May, Bucks; and in June, the wettest 
are Oxford and Berks. 
The complete paper contains the details from which the above summary has 
been compiled, and is accompanied by a map showing the position of the rainfall 
stations and their height above mean sea-level. 
TUESDAY, SEPTEMBER 19, 
The following Papers and Report were read :— 
1. Ona Gravity Balance. By Professor R. TureLratt, F.RAS., and 
Professor J. A. Potiock.! 
2. Report on Llectrical Standards. See Reports, p. 240. 
} This paper will be published in the Philosophical Transactions of the Royal 
Society. ; es 
vUuU2 
